We bought house 18 months ago with an en-suite with a Bristan Sonique shower control (thermostatically controlled mixer). The shower was fed by a New Team Duraspeed Shower Pump (1.5bar) and about 7 metres of up and over ½ inch pipe. The
pump is fed by gravity from a roof tank about 1.5 metres above the shower head. On 21/1/2018 the pump started to leak through its casing. Before that it worked fine, if somewhat noisily.
We called a plumber and he advised replacing the pump with a Stuart Turner. I bought a Stuart Turner Showermate Eco S Positive Head Twin Shower Pump 1.5bar and he installed it.
Unfortunately things are not working properly. The pump pulses off and on.
The plumber spent over 2 hours trying to resolve this.
Hot and cold both get through to the shower by gravity when the pump is turned off.
There is an access panel behind the shower with isolation valves for the shower. He closed the valves, disconnected the pipework below the valves and then tested the flow with the pump on to that point. No problem.
He removed the shower hose and head. Turning on the shower still caused the pump to pulse.
The problem would appear to be the resistance to the flow from the thermostatic shower control. The valve still works fine with just a gravity feed. Stripping the valve and soaking it in descaler has not
What have I done wrong? What do I do now?